虽然CodePlex上的WPF扩展的XXX ToolKit源码中有一个CheckListBox控件，但是，就看它那源代码，也过于复杂了。并且，我也希望自己来编写一个CheckListBox控件。

所谓CheckListBox控件嘛，就是既可以Select又可以Check的ListBox控件。有人会说，不用写控件，自定义一个ListBoxItem的模板就行了，也确实可以这样做，不过，还是有些问题的，如果只是重定义ListBoxItem的模板，那仅仅是为其UI上加了个可以显示一个“勾”的东东而已，而对于逻辑是没有任何变化。

既然要可以Select又能Check，那显然只是重定义模板是不行的。ListBoxItem类本身有一个IsSelected属性，指示列表项是否被选中，而且，人家在ListBox中也有一个SelectedItems属性，可以获得ListBox控件的当前选中的所有项。

很明显，我们的CheckableListBoxItem要有一个IsChecked属性来指示列表项是否被Check，而在CheckListBox控件上应当有一个CheckedItems属性，可以获取当前所有被Checked的项。

刚开始，我是计划让CheckableListBoxItem从ContentControl类派生，CheckListBox从ItemsControl派生。但是，转念一想，其实这所谓的可以Check的ListBox就是ListBox和CheckBox控件的结合体，而大多数功能与ListBox控件相似，是没有必要自己重新来写ListBox的功能，所以，后来我决定：CheckableListBoxItem从ListBoxItem类派生，CheckListBox则从ListBox派生，但其中的项目的容器已经不是ListBox了，而是我继承的CheckableListBoxItem类。

有一点我们要明确的，熟悉WPF的朋友都知道，在WPF/SL/WP/Store App这一堆使用XAML布局UI的开发框架中，列表控件所获出来的项并不是项的容器，除非你在ListBox中直接用ListBoxItem作为对象加进列表控件的集合中，不然会根据你添加的项返回对应的内容，如果你放进去的是String，那么拿出来也是String；你放进去的是int，拿出来的也是int。

至于说为什么要这样做嘛，很多人不解了，ListBox里面明明是放ListBoxItem的，怎么直接返回其对象了？WPF说的是啥？MVVM，既然要MVVM，当然是你在绑定了哪个对象，取出来还是那个对象好了，这样就方便了。

好了，理论的扯完了，就上代码吧。

using System;
using System.Collections.Generic;
using System.Collections;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Data;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using System.Windows.Navigation;
using System.Windows.Shapes;
using System.Collections.ObjectModel;namespace MyListBox
{[StyleTypedProperty(Property = "ItemContainerStyle", StyleTargetType = typeof(CheckableListBoxItem))]public class CheckListBox : ListBox{ObservableCollection<object> m_checkedItems = null;Type m_itemContainerType = typeof(FrameworkElement);//项容器的类型public CheckListBox(){m_checkedItems = new ObservableCollection<object>();// 从CheckListBox类附加的特性中获取项目容器的类型var attr = this.GetType().GetCustomAttributes(typeof(StyleTypedPropertyAttribute), false);if (attr != null && attr.Length != 0){StyleTypedPropertyAttribute sty = attr[0] as StyleTypedPropertyAttribute;if (sty != null){this.m_itemContainerType = sty.StyleTargetType;}}}public static DependencyProperty CheckedItemsProperty = DependencyProperty.Register("CheckedItems", typeof(IList), typeof(CheckListBox), new PropertyMetadata(null));public IList CheckedItems{get { return (IList)GetValue(CheckedItemsProperty); }}/// <summary>/// 创建项目容器/// </summary>protected override DependencyObject GetContainerForItemOverride(){return Activator.CreateInstance(this.m_itemContainerType) as DependencyObject;}/// <summary>/// 当从项目创建项容时，/// 为项目容器注册事件处理。/// </summary>protected override void PrepareContainerForItemOverride(DependencyObject element, object item){CheckableListBoxItem ckItem = element as CheckableListBoxItem;ckItem.Checked += clbitem_Checked;ckItem.UnChecked += clbitem_UnChecked;base.PrepareContainerForItemOverride(element, item);}/// <summary>/// 当项容被清空时，/// 解除事件处理程序。/// </summary>protected override void ClearContainerForItemOverride(DependencyObject element, object item){CheckableListBoxItem ckItem = element as CheckableListBoxItem;ckItem.Checked -= clbitem_Checked;ckItem.UnChecked -= clbitem_UnChecked;base.ClearContainerForItemOverride(element, item);}void clbitem_UnChecked(object sender, RoutedEventArgs e){CheckableListBoxItem citem = (CheckableListBoxItem)e.Source;object value = citem.Content;m_checkedItems.Remove(value);SetValue(CheckedItemsProperty, m_checkedItems);}void clbitem_Checked(object sender, RoutedEventArgs e){CheckableListBoxItem citem = (CheckableListBoxItem)(e.Source);object value = citem.Content;if (m_checkedItems.SingleOrDefault(o => object.ReferenceEquals(o, value)) == null){m_checkedItems.Add(value);SetValue(CheckedItemsProperty, m_checkedItems);}}}public class CheckableListBoxItem : ListBoxItem{static CheckableListBoxItem(){DefaultStyleKeyProperty.OverrideMetadata(typeof(CheckableListBoxItem),new FrameworkPropertyMetadata(typeof(CheckableListBoxItem)));}#region 属性public static readonly DependencyProperty IsCheckedProperty =DependencyProperty.Register("IsChecked", typeof(bool), typeof(CheckableListBoxItem), new PropertyMetadata(new PropertyChangedCallback(IsCheckedPropertyChanged)));private static void IsCheckedPropertyChanged(DependencyObject d, DependencyPropertyChangedEventArgs e){CheckableListBoxItem lt = d as CheckableListBoxItem;if (lt !=null){if (e.NewValue != e.OldValue){bool b = (bool)e.NewValue;if (b== true){lt.RaiseCheckedEvent();}else{lt.RaiseUnCheckedEvent();}}}}/// <summary>/// 获取或设置控件是否被Check/// </summary>public bool IsChecked{get { return (bool)GetValue(IsCheckedProperty); }set { SetValue(IsCheckedProperty, value); }}#endregion#region 事件public static readonly RoutedEvent CheckedEvent =EventManager.RegisterRoutedEvent("Checked", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(CheckableListBoxItem));/// <summary>/// 当控件被Check后发生的事件/// </summary>public event RoutedEventHandler Checked{add{AddHandler(CheckedEvent, value);}remove{RemoveHandler(CheckedEvent, value);}}void RaiseCheckedEvent(){RoutedEventArgs arg = new RoutedEventArgs(CheckableListBoxItem.CheckedEvent);RaiseEvent(arg);}public static readonly RoutedEvent UnCheckedEvent = EventManager.RegisterRoutedEvent("UnChecked", RoutingStrategy.Bubble, typeof(RoutedEventHandler), typeof(CheckableListBoxItem));/// <summary>/// 当控件未被Check后发生/// </summary>public event RoutedEventHandler UnChecked{add { AddHandler(UnCheckedEvent, value); }remove { RemoveHandler(UnCheckedEvent, value); }}void RaiseUnCheckedEvent(){RaiseEvent(new RoutedEventArgs(UnCheckedEvent));}#endregion}}

定义模板的XAML的核心部分如下：

    <ControlTemplate x:Key="toggleButtonTmp" TargetType="{x:Type ToggleButton}"><Border Background="{TemplateBinding Background}" BorderThickness="{TemplateBinding BorderThickness}" BorderBrush="{TemplateBinding BorderBrush}"><Path x:Name="pc" Opacity="0" Margin="{TemplateBinding Padding}" Stretch="Uniform" Stroke="{TemplateBinding Foreground}" StrokeThickness="2.68"><Path.Data><PathGeometry><PathFigure StartPoint="0,13"><PolyLineSegment Points="13,20 20,0"/></PathFigure></PathGeometry></Path.Data></Path></Border><ControlTemplate.Triggers><Trigger Property="IsChecked" Value="True"><Setter TargetName="pc" Property="Opacity" Value="1.0"/></Trigger></ControlTemplate.Triggers></ControlTemplate><Style TargetType="{x:Type local:CheckableListBoxItem}"><Setter Property="Padding" Value="14,2,0,2"/><Setter Property="Background" Value="{DynamicResource {x:Static SystemColors.WindowBrushKey}}" /><Setter Property="Template"><Setter.Value><ControlTemplate TargetType="{x:Type local:CheckableListBoxItem}"><Border x:Name="bd" Background="{TemplateBinding Background}" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"><Grid Margin="2.1"><Grid.ColumnDefinitions><ColumnDefinition Width="auto"/><ColumnDefinition Width="*"/></Grid.ColumnDefinitions><ToggleButton x:Name="tog" Grid.Column="0" Margin="1" Width="18" Height="18" IsChecked="{Binding IsChecked, Mode=TwoWay, RelativeSource={RelativeSource TemplatedParent}}" Template="{StaticResource toggleButtonTmp}" Background="{StaticResource togglebtn_bg}"/><ContentPresenter Grid.Column="1" Margin="{TemplateBinding Padding}" Content="{TemplateBinding Content}" ContentTemplate="{TemplateBinding ContentTemplate}" ContentTemplateSelector="{TemplateBinding ContentTemplateSelector}" HorizontalAlignment="{Binding HorizontalContentAlignment, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ItemsControl}}}" VerticalAlignment="{Binding VerticalContentAlignment, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type ItemsControl}}}"/></Grid></Border><ControlTemplate.Triggers><Trigger Property="ListBoxItem.IsSelected" Value="True"><Setter Property="Background" TargetName="bd"  Value="{StaticResource selectedItemBrush}" /><Setter Property="Control.Foreground" Value="{StaticResource selectedForeBrush}"/><Setter TargetName="tog" Property="Control.Foreground" Value="{StaticResource selectedTgbtnFore}"/></Trigger><MultiTrigger ><MultiTrigger.Conditions><Condition Property="UIElement.IsMouseOver" Value="True"/><Condition Property="ListBoxItem.IsSelected" Value="False"/></MultiTrigger.Conditions> <Setter TargetName="bd" Property="Background" Value="{StaticResource hoverBrush}"/></MultiTrigger></ControlTemplate.Triggers></ControlTemplate></Setter.Value></Setter></Style>

接下来就是测试一下控件。

    <Grid><Grid.ColumnDefinitions><ColumnDefinition/><ColumnDefinition/></Grid.ColumnDefinitions><local:CheckListBox x:Name="lb" Grid.Column="0" SelectionMode="Multiple" ItemTemplate="{StaticResource stuTmp}"/><Grid Grid.Column="1"><Grid.RowDefinitions><RowDefinition Height="auto"/><RowDefinition/><RowDefinition Height="auto"/><RowDefinition/></Grid.RowDefinitions><TextBlock Grid.Row="0" Text="被Checked的项：" FontSize="17" Margin="5,3,0,2"/><ListBox Grid.Row="1" ItemsSource="{Binding Path=CheckedItems,ElementName=lb}" Margin="5" ItemTemplate="{StaticResource stuTmp}"/><TextBlock Grid.Row="2" Text="被Selected的项：" FontSize="17" Margin="5,0,0,2"/><ListBox Grid.Row="3" Margin="5" ItemsSource="{Binding Path=SelectedItems,ElementName=lb}" ItemTemplate="{StaticResource stuTmp}"/></Grid></Grid>

******************************************************************

            lb.ItemsSource = new Student[]{new Student{ Name="狗", Age=30 },new Student{ Name="兔", Age=31 },new Student{ Name="蛇", Age=18 },new Student{ Name="鸡", Age=22 },new Student{ Name="猫", Age=24 },new Student{ Name="青蛙", Age=28 },new Student{ Name="猴", Age=19 }};

代码不完全，但主要的我都放出来了，随后我把所有代码都上传到【资源】中，相当优惠，0积分下载。

下图是最终的结果。